The present invention relates to apparatus and methods for the repair of Porsche automobile engines and, more particularly, to a replacement oil drain tube for fitting between the cylinder head and crankcase of such engines, the replacement tube being designed for installation on such engines without the removal of the cylinder head.
Porsche automobile engines are opposed cylinder, air cooled engines including a main engine block incorporating a crankcase and its associated crankshaft and fitted with opposed, outwardly extending cylinder assemblies fitted with cylinder heads mounting overhead cam shafts, rocker arms, and valve assemblies. These elements within the cylinder head assembly are pressure lubricated, leading to an accumulation of oil which drains to the crankcase through plural oil drain tubes. The tubes interconnect the head assembly and crankcase, outboard of and below the cylinder assemblies. These engines are designed with exhaust manifold assemblies positioned below the cylinder and head assemblies, further outboard from the cylinder than the oil drain tubes, so that the oil drain tubes are positioned between these manifolds and the engine cylinders. As a consequence, the oil drain tubes supplied by the manufacturer are subject to extremely high temperatures and large temperature fluctuations. The tubes are sealed, using gasket material, to both the engine crankcase and head assembly, and the seals, as well as the oil drain tubes themselves, are subject to failure and resultant oil leakage.
In the case of this particular engine, such oil leakage is particularly objectionable, since the oil commonly leaks onto the hot exhaust manifold where it burns, creating smoke and fumes.
In the past, repair of failing oil drain tubes has required the removal of the cylinder head assembly, so that even though the oil drain tubes themselves are a relatively inexpensive replacement part, the labor cost involved in repairing oil leaks is quite high.